Datasheet

170
ATmega8535(L)
2502K–AVR–10/06
Examples of Baud Rate
Setting
For standard crystal and resonator frequencies, the most commonly used baud rates for
asynchronous operation can be generated by using the UBRR settings in Table 69.
UBRR values which yield an actual baud rate differing less than 0.5% from the target
baud rate, are bold in the table. Higher error ratings are acceptable, but the Receiver will
have less noise resistance when the error ratings are high, especially for large serial
frames (see “Asynchronous Operational Range” on page 160). The error values are cal-
culated using the following equation:
Error[%]
BaudRate
Closest Match
BaudRate
-------------------------------------------------------- 1–
⎝⎠
⎛⎞
100%•=
Table 69. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
f
osc
= 1.0000 MHz f
osc
= 1.8432 MHz f
osc
= 2.0000 MHz
U2X = 0 U2X = 1 U2X = 0 U2X = 1 U2X = 0 U2X = 1
UBRR Error UBRR Error UBRR Error UBRR Error UBRR Error UBRR Error
2400 250.2%510.2%470.0%950.0%510.2%1030.2%
4800 120.2%250.2%230.0%470.0%250.2%510.2%
9600 6 -7.0% 12 0.2% 11 0.0% 23 0.0% 12 0.2% 25 0.2%
14.4k 3 8.5% 8 -3.5% 7 0.0% 15 0.0% 8 -3.5% 16 2.1%
19.2k 2 8.5% 6 -7.0% 5 0.0% 11 0.0% 6 -7.0% 12 0.2%
28.8k 1 8.5% 3 8.5% 3 0.0% 7 0.0% 3 8.5% 8 -3.5%
38.4k 1 -18.6% 2 8.5% 2 0.0% 5 0.0% 2 8.5% 6 -7.0%
57.6k 0 8.5% 1 8.5% 1 0.0% 3 0.0% 1 8.5% 3 8.5%
76.8k – – 1 -18.6% 1 -25.0% 2 0.0% 1 -18.6% 2 8.5%
115.2k – – 0 8.5% 0 0.0% 1 0.0% 0 8.5% 1 8.5%
230.4k––––––00.0%––––
250k––––––––––00.0%
Max
(1)
62.5 kbps 125 kbps 115.2 kbps 230.4 kbps 125 kbps 250 kbps
1. UBRR = 0, Error = 0.0%